Hybrid and electric vehicles (HEVs) typically include an alternating current (AC) electric motor which is driven by a direct current (DC) power source, such as a storage battery. Motor windings of the AC electric motor can be coupled to power inverter module(s) which perform a rapid switching function to convert the DC power to AC power which drives the AC electric motor, which in turn drives a shaft of HEV's drivetrain. Traditional HEVs implement two three-phase pulse width modulated (PWM) inverter modules and two three-phase AC motors each being driven by a corresponding one of the three-phase PWM inverter modules that it is coupled to. Each three-phase PWM inverter module generates three-phase currents (I_as, I_bs, I_cs) that drive one of the three-phase AC motors that the particular three-phase PWM inverter module is connected to. In particular, each three-phase PWM inverter module includes three inverter sub-modules, where each of the inverter sub-modules generates one of the three-phase currents (I_as, I_bs, I_cs) that is provided to a motor winding of the AC motor driven by that the three-phase PWM inverter module.
In some situations, a connection between the inverter module and its corresponding three-phase AC motor can fail. This can happen, for example, due to a disconnection of a wire to/in the three-phase AC motor.
An existing diagnostic method can detect an open circuit condition involving the three-phase PWM inverter module only if at least one of the three-phase currents (I_as, I_bs, I_cs) output by one of inverter sub-modules is zero when a current command is above a threshold. Thus, this diagnostic method works only when one (or more) of the inverter sub-modules does not generate a three-phase current (i.e., its output three-phase current has a value of zero).
Accordingly, it is desirable to provide other diagnostic methods, systems and apparatus for detecting abnormal operation of a three-phase PWM inverter module. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.